Nanometer material is a new structure in twentieth Century 80 time metaphase development material, refers to components, composed of veryfine grain characteristic dimension size is 1nm - l00nm single crystal orpolycrystal. Because of a very fine grain size, and a large number of in thequantum size effect, the grain boundaries and inside the grains defect center atom has the small size effect, surface effect and the macroscopic quantum tunnel effect and so on, compared with micron materials and nano materials with the same composition, with many unique properties and new rules in catalysis, optical, magnetic, mechanical aspects, and thus become the focus of material science and condensed matter physics in the field of.In recent years, the people of the nano material preparation, properties and application prospects of structure, carried out extensive and in-depth study.Scientists have nano materials will be known as the "twenty-first Century's most promising material".
So far the method of preparing nanometer particles there have been dozens of kinds. According to the way of nanoparticle formation, can be divided into two categories, namely the coarse particles by crushing and become a super particle crushing method and composed of atoms,molecules or ions through nucleation, formed granulating method ofultrafine particles. According to the raw material condition is different, can be divided into solid method, liquid phase method and gas phase methodthree. According to the super particles form if there are new material composition of the generation process, and people will be divided intophysical methods and chemical methods. Crushing method usually uses mechanical means gradually metal or alloy large particles are ground into fine powder. Is a typical representative of the solid phase, physical method.Gas phase law through the induction of raw gas chemical reaction,generate solid matter particles can be collected, belonging to the chemicalgranulation method.
The method of liquid phase is generated, extraction of ultrafine particlesfrom the chemical solution. According to the material composition andpreparation methods on the different, can be a physical method, can also be a chemical method; can be both granulation, sometimes also can becrushing method.
